RubyPrefetcher.hh

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/*
 * Copyright (c) 2020 Inria
 * Copyright (c) 2020 ARM Limited
 * All rights reserved
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
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 * modified or unmodified, in source code or in binary form.
 *
 * Copyright (c) 1999-2012 Mark D. Hill and David A. Wood
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
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 * redistributions in binary form must reproduce the above copyright
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#ifndef __MEM_RUBY_STRUCTURES_PREFETCHER_HH__
#define __MEM_RUBY_STRUCTURES_PREFETCHER_HH__
 
// Implements Power 4 like prefetching
 
#include <bitset>
 
#include "base/circular_queue.hh"
#include "base/statistics.hh"
#include "mem/ruby/common/Address.hh"
#include "mem/ruby/network/MessageBuffer.hh"
#include "mem/ruby/slicc_interface/AbstractController.hh"
#include "mem/ruby/slicc_interface/RubyRequest.hh"
#include "mem/ruby/system/RubySystem.hh"
#include "params/RubyPrefetcher.hh"
#include "sim/sim_object.hh"
#include "sim/system.hh"
 
#define MAX_PF_INFLIGHT 8
 
namespace gem5
{
 
namespace ruby
{
 
class PrefetchEntry
{
    public:
        PrefetchEntry()
        {
            // default: 1 cache-line stride
            m_stride   = (1 << RubySystem::getBlockSizeBits());
            m_use_time = Cycles(0);
            m_is_valid = false;
        }
 
        Addr m_address;
 
        int m_stride;
 
        Cycles m_use_time;
 
        bool m_is_valid;
 
        RubyRequestType m_type;
 
        std::bitset<MAX_PF_INFLIGHT> requestIssued;
        std::bitset<MAX_PF_INFLIGHT> requestCompleted;
};
 
class RubyPrefetcher : public SimObject
{
    public:
        typedef RubyPrefetcherParams Params;
        RubyPrefetcher(const Params &p);
        ~RubyPrefetcher() = default;
 
        void issueNextPrefetch(Addr address, PrefetchEntry *stream);
        void observePfHit(Addr address);
        void observePfMiss(Addr address);
 
        void observeMiss(Addr address, const RubyRequestType& type);
 
        void print(std::ostream& out) const;
        void setController(AbstractController *_ctrl)
        { m_controller = _ctrl; }
 
    private:
        struct UnitFilterEntry
        {
            Addr addr;
            uint32_t hits;
 
            UnitFilterEntry(Addr _addr = 0)
              : addr(_addr), hits(0)
            {
            }
        };
 
        struct NonUnitFilterEntry : public UnitFilterEntry
        {
            int stride;
 
            NonUnitFilterEntry(Addr _addr = 0)
              : UnitFilterEntry(_addr), stride(0)
            {
            }
 
            void
            clear()
            {
                addr = 0;
                stride = 0;
                hits = 0;
            }
        };
 
        uint32_t getLRUindex(void);
 
        void initializeStream(Addr address, int stride,
            uint32_t index, const RubyRequestType& type);
 
        PrefetchEntry* getPrefetchEntry(Addr address,
            uint32_t &index);
 
        bool accessUnitFilter(CircularQueue<UnitFilterEntry>* const filter,
            Addr line_addr, int stride, const RubyRequestType& type);
 
        bool accessNonunitFilter(Addr line_addr, const RubyRequestType& type);
 
        Addr pageAddress(Addr addr) const;
 
        uint32_t m_num_streams;
        std::vector<PrefetchEntry> m_array;
 
        uint32_t m_train_misses;
        uint32_t m_num_startup_pfs;
 
        CircularQueue<UnitFilterEntry> unitFilter;
 
        CircularQueue<UnitFilterEntry> negativeFilter;
 
        CircularQueue<NonUnitFilterEntry> nonUnitFilter;
 
        bool m_prefetch_cross_pages;
 
        AbstractController *m_controller;
 
        const Addr m_page_shift;
 
        struct RubyPrefetcherStats : public statistics::Group
        {
            RubyPrefetcherStats(statistics::Group *parent);
 
            statistics::Scalar numMissObserved;
            statistics::Scalar numAllocatedStreams;
            statistics::Scalar numPrefetchRequested;
            statistics::Scalar numHits;
            statistics::Scalar numPartialHits;
            statistics::Scalar numPagesCrossed;
            statistics::Scalar numMissedPrefetchedBlocks;
        } rubyPrefetcherStats;
};
 
} // namespace ruby
} // namespace gem5
 
#endif // __MEM_RUBY_STRUCTURES_PREFETCHER_HH__